Adaptive array control is implemented in a radio communication system, such as a mobile communication system, so that an increased number of radio communication terminals can be accommodated in the radio communication system, for example. In the adaptive array control, the directivity of an array antenna having multiple antenna elements is adaptively controlled by a radio communication device, such as a radio base station, according to the position of a radio communication terminal.
Meanwhile, in time division duplex (TDD) that allows received radio signals and transmission radio signals to be allocated to the site frequency band, a radio base station can use a reception weight, which is calculated based on a radio signal received from a radio communication terminal, as a transmission weight without making any corrections. However, if the reception weight is used as-is as the transmission weight while the radio communication terminal is moving at high speed (e.g., 100 km/h or faster), the following problem may arise. Specifically, a proper directivity in accordance with the position of the radio communication terminal cannot be obtained.
To avoid such problem, there is known a method in which the radio base station corrects the transmission weight by detecting a Doppler frequency, namely, a fading rate, that represents a movement speed of the radio communication terminal (for example, Patent Document 1).    Patent Document 1: JP-A 2003-32167 (pages 7 and 8, FIG. 1)